The one time I tried trailering with the “thick end first” the spreaders made contact with the fore-deck and did some damage. No Disgrace’s advice is correct.
I generally have about a metre and a half sticking out behind the transom, which is probably a bit illegal but otherwise I donk the roof of my car with the top of the mast if there are any hills/slopes to climb. I have a child’s red bucket I tie on the foot of the mast and tuck all the loose ends of halyards inside.